Replacing the thermal paste is one of those PC maintenance tasks most people, including myself, don’t think about until performance seems off. You apply it when you first build your PC, or it comes pre-applied from the factory in the case of CPU coolers and GPUs, and it quietly does its job for years without any obvious signs of wear. The thing is, thermal paste doesn’t last forever, even the expensive ones. Over time, it dries out, loses its consistency, or simply stops performing as well as it did when it was fresh.